PURPOSE: To surely and smoothly execute the remote operation of a measuring unit by means of an operation unit arranged on a remote place by providing an optical communication means and mutually exchanging information between the measuring unit and the operating unit through space.

CONSTITUTION: The measuring unit 10 and the operating unit 40 are remotely arranged from each other, and in case of mutually exchanging information through the optical communication means 30, a work and data to be found out are set up on the unit 10 at first. Then, command information is outputted as a serial data electric signal from a transmitter 48 based on a program stored in a CPU 44 of the unit 40 and an optical data signal is generated from a light emitter 36 to a light reflecting plate 34. The plate 34 arranged on the ceiling of a measuring room reflects light at a prescribed angle and transmits the optical data signal to a receiver 29 through a photo-detector 32 in the unit 10 side. The command information received by the receiver 29 is converted into an electric signal and stored in a CPU 26, a timely counting circuit 23 is driven at an optimum time, and prescribed processing is executed. Thus, the measuring unit 10 can be surely, smoothly and remotely operated.